Sudden cardiac arrest (SCA) due to ventricular arrhythmia (VA) can result in sudden cardiac death (SCD), SCA accounts for 50% of all death from cardiovascular causes and strikes 250,000-350,000 victims in the United States every year. Implantable cardioverter-defibrillators (ICDs) are the treatment of choice for patients at risk for SCA, effectively terminating ventricular tachychardia or ventricular fibrillation (VTNF). The risk for SCA is highest in patients with significantly depressed left ventricular systolic function (left ventricular ejection fraction LVEF≦35%), and the overwhelming majority of SCA cases occur in heart failure with preserved ejection fraction (HFpEF) patients. Moreover, depressed LVEF only identifies approximately one-third of all victims of SCD.
Vectorcardiography has proven to be a useful, but underutilized diagnostic tool, providing similar diagnostic information as the traditional 12-lead electrocardiogram (ECG). In certain cases, vectorcardiograms (VCGs) have been shown to be a more powerful diagnostic tool than the ECG, such as in diagnosing acute myocardial infarction in the presence of bundle branch blocks. However, it rarely used in a clinical setting, and has limitations in detecting VA. For example, it has been demonstrated through evaluation of human transmural three dimensional (3D) ventricular activation maps that interrogation of the terminal QRS-ST segment of cardiac cycle SAECG in VCG fails to detect the cardiac signals generated by the myocardium which are responsible for VA in 95% of cases.
There remains, therefore, a need for improved detection and prediction of cardiac events, especially in patients who have previously suffered such an event.